Research Papers

Design and Analysis of a Novel Split Sliding Variable Nozzle for Turbocharger Turbine

[+] Author and Article Information
Liangjun Hu

Research and Innovation Center,
Ford Motor Company,
Dearborn, MI 48124
e-mail: lhu4@ford.com

Harold Sun

Research and Innovation Center,
Ford Motor Company,
Dearborn, MI 48124
e-mail: hsun3@ford.com

James Yi

Research and Innovation Center,
Ford Motor Company,
Dearborn, MI 48124
e-mail: jyi1@ford.com

Eric Curtis

Research and Innovation Center,
Ford Motor Company,
Dearborn, MI 48124
e-mail: ecurtis@ford.com

Jizhong Zhang

Diesel Engine Turbocharging Laboratory,
China North Engine Research Institute,
Tianjin 300400, China
e-mail: dtzjz@163.com

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received November 3, 2017; final manuscript received November 25, 2017; published online April 6, 2018. Editor: Kenneth Hall.

J. Turbomach 140(5), 051006 (Apr 06, 2018) (10 pages) Paper No: TURBO-17-1205; doi: 10.1115/1.4038878 History: Received November 03, 2017; Revised November 25, 2017

Variable geometry turbine (VGT) has been widely applied in internal combustion engines to improve engine transient response and torque at light load. One of the most popular VGTs is the variable nozzle turbine (VNT) in which the nozzle vanes can be rotated along the pivoting axis and thus the flow passage through the nozzle can be adjusted to match with different engine operating conditions. One disadvantage of the VNT is the turbine efficiency degradation due to the leakage flow in the nozzle endwall clearance, especially at small nozzle open condition. With the purpose to reduce the nozzle leakage flow and to improve turbine stage efficiency, a novel split sliding variable nozzle turbine (SSVNT) has been proposed. In the SSVNT design, the nozzle is divided into two parts: one part is fixed and the other part can move along the partition surface. When sliding the moving vane to large radius position, the nozzle flow passage opens up and the turbine has high flow capacity. When sliding the moving vane to small radius position, the nozzle flow passage closes down and the turbine has low flow capacity. As the fixed vane does not need endwall clearance, the leakage flow through the nozzle can be reduced. Based on calibrated numerical simulation, there is up to 12% turbine stage efficiency improvement with the SSVNT design at small nozzle open condition while maintaining the same performance at large nozzle open condition. The mechanism of efficiency improvement in the SSVNT design has been discussed.

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Fig. 1

Vehicle driving cycle on matched turbine map

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Fig. 2

Illustration of SSVNT

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Fig. 3

Illustrations of nozzle clearance and leakage flow of base VNT

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Fig. 4

Mesh and CFD model of a SSVNT design

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Fig. 5

Nozzle insert at small nozzle opening

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Fig. 6

Nozzle endwall clearance on the hub side

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Fig. 7

Illustration of turbocharger flow bench for turbine performance test

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Fig. 8

Comparison of simulated and tested turbine performance: (a) pressure ratio-mass flow and (b) pressure ratio-efficiency

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Fig. 9

Different base nozzle shapes

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Fig. 10

Partition surface design of SSVNT

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Fig. 11

Flow loss comparisons between pressure side and suction side of the conventional VNT

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Fig. 12

Main parameters of nozzle

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Fig. 13

Comparison of turbine aero performance: (a) turbine mass flow and (b) turbine efficiency

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Fig. 14

Nozzle endwall leakage flow comparison at 13% open condition: (a) base VNT and (b) SSVNT

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Fig. 15

LFR comparison at 13% open condition

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Fig. 16

Nozzle vane total pressure loss comparison: (a) SSVNT, (b) VNT, and (c) nozzle total pressure loss

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Fig. 17

Rotor inlet incidence angle comparison

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Fig. 18

Flow separation at 10% spanwise location: (a) base VNT and (b) SSVNT

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Fig. 19

Boundary layer flow comparison on the hub and impeller suction side: (a) base VNT and (b) SSVNT

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Fig. 20

Loading comparison between base VNT and SSVNT: (a) hub, (b) middle-span, and (c) shroud



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